Cheese whey utilization for biosurfactant production: evaluation of bioprocessing strategies using novel Lactobacillus strains

Microbial surfactants have induced research and industrial interest recently, owing to their significant advantages over the chemically produced counterparts. The pursuit of novel biosurfactant producers includes first the isolation and screening, followed by studies on fermentation strategies. The utilization of non-pathogenic strains, like lactobacilli, will expand the potential for targeted and innovative food-oriented applications. Hence, this study undertakes the evaluation of different bioprocessing parameters and schemes for biosurfactant production using Lactobacillus strains selected from a previous screening study. Cheese whey permeate (CWP) was used as a low-cost nutrient supplement, in the context of valorizing food industry by-products towards the development of biorefinery concepts. Microplates and shake flasks experiments were performed to assess the effect of pH, temperature and CWP supplementation with micronutrients and exogenous nitrogen sources. Two different media were applied in bioreactor studies, along with several fermentation conditions and significant biosurfactant production was evidenced via surface tension reduction (< 30 mN/m). Among the Lactobacillus strains studied, Limosilactobacillus fermentum ACA-DC 0183 demonstrated the maximum surface tension reduction (34.9 mN/m) after 32 h, observed even at the early hours of fermentation (4 h). Notably, the majority of the experiments indicated an inverse correlation between biosurfactants and lactic acid production. The produced biosurfactants were also extracted and partially characterized. The results presented hereof communicate promising findings in the context of mitigating the costs associated with biosurfactant production and foster the development of food industry by-products refining to enhance the circularity and sustainability of food systems.